1. Field
Disclosed herein is novel electrochromic materials and electrochromic devices fabricated using the electrochromic materials. More specifically, the electrochromic materials produce various colors.
2. Description of the Related Art
Electrochromism is the phenomenon displayed by some chemical species which have a reversibly changeable color when a voltage is applied thereto. A material capable of undergoing reversible changes of optical properties by the electrochemical redox reaction accompanying such electrochromic properties is called an electrochromic material. That is, the electrochromic material may not have a color in the absence of an electric field and then may display a certain color when an electric field is applied, e.g., by an external source, and vice versa.
Electrochromic devices taking advantage of such an electrochromic phenomenon have various advantages such as high reflectivity without a need for an external light source, excellent flexibility and portability, and the feasibility of weight reduction, and are therefore expected to have promising applications for various flat-panel displays (“FPDs”). In particular, electrochromic devices are receiving a great deal of attention, due to high applicability to E-paper which is recently under intensive research and study, as an electronic medium capable of replacing paper.
Examples of the electrochromic materials may include inorganic compounds such as tungsten oxides, molybdenum oxides, and the like, and organic compounds such as pyridine, aminoquinone and azine compounds. However, even though blue and green electrochromic materials are known in such a nano-electrochromic type, red electrochromic materials are not yet known.
In comparison with inorganic electrochromic materials, organic electrochromic materials are disadvantageous in terms of long-term stability, but have advantages in that they are applicable to flexible substrates and can be used to form thin films by wet processing. Based on these advantages, a great deal of research has been conducted on organic electrochromic materials.
On the other hand, a combination of red, green and blue is required to achieve full-color electrochromic devices. However, few red electrochromic materials have been discovered to date. Under such circumstances, there exists a need to develop red electrochromic materials.